The present invention relates generally to round balers for forming a cylindrical bale of crop material, and more particularly to apparatus for continuously monitoring bale size (diameter) whereby the operator may select a desired bale size and/or netting may be dispensed to wrap a bale, the length of netting dispensed being dependent on the size of the bale.
Round balers for forming cylindrical bales of crop material have long been known in the art. It has been conventional to provide such balers with a twine dispensing means for wrapping a formed bale with twine so that the bale will maintain its shape and compactness after being ejected from the baler. A recent development, exemplified by the Claas Model 44 round baler, is the provision of a net dispenser, rather than a twine dispenser, whereby a formed bale is wrapped with a length of net material. As exemplified by U.S. Pat. No. 4,603,379 it is also known to automate round balers so that when a full bale is formed the wrapping apparatus is activated to wrap the bale and cut the wrapping material. While these devices are satisfactory for automatically wrapping full bales, the size of a full bale is fixed because sensor switches are utilized to determine when a bale has reached a predetermined size. On the other hand, it is frequently desirable to automatically wrap a completed bale even though it is not large enough to actuate the full bale sensor. This might occur, for example, when the farmer wishes to form smaller bales to better fit into a truck or storage space of given dimensions, or when only a partial bale has been formed at the end of a field. Thus, it is desirable to be able to continuously monitor bale size so that an operator may select the size of bales to be formed, and the bales may be wrapped with the minimum amount of wrapping material required to hold the bale intact.
In the copending application of Richard P. Strosser et al. Ser. No. 46,614, now U.S. Pat. No. 4,748,802, filed May 7, 1987 there is disclosed an apparatus for monitoring the shape of a bale by sensing the size of a bale and lighting first one and then the other of two indicators to signal the operator to steer right or steer left along a windrow, the result being that crop material is added toward first one end and then the other end of the bale being formed. This enables the building up of a generally cylindrical bale of uniform density. However, the mechanism disclosed therein senses the bale diameter only at fixed, equally spaced, bale diameters. When heavy crop conditions are encountered at small bale diameters there is a rapid lighting of first one and then the other indicator at a rate too fast for the operator to follow. Also, the last few inches of bale diameter are built up more toward one end of the bale thus giving a bale of non-uniform diameter. The continuous bale size sensor disclosed herein permits the lighting of the indicators at nonfixed increments of bale diameter, the increments being larger at the smaller bale diameters. This alleviates both the problem of too-fast switching between lights and the problem of non-uniform diameter.
The bale size sensor disclosed in the Strosser et al. application is actuated by a serpentine arm which maintains tension in the apron as bale size increases. As the apron and its support mechanism wears, the bale size sensor indicates a bale size greater than the actual size of the bale in the baler. The continuous bale size sensor provided by the present invention permits automatic compensation for wear so that a true indication of bale size is always available.